ES2963510T3 - Collision avoidance method and system - Google Patents

Abstract

The present invention relates to a collision avoidance method for a host vehicle, the method comprising: detecting (S102) a target (104) in the vicinity of the vehicle; determining (S104) that the host vehicle is traveling on a collision course (106) with the target; detecting a steering action initiated by the user to direct the vehicle to one side of the target; determining a degree of understeer of the host vehicle; when the degree of understeer exceeds a first understeer threshold, controlling a steering control system of the vehicle to counteract the steering action initiated by the user to thereby reduce the degree of understeer. The invention further relates to an evasive steering system. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Collision avoidance method and system

Field of Invention

The present invention relates to a collision avoidance method and an evasive steering system configured to provide an intervention action for a host vehicle.

Background of the Invention

Today, vehicles are becoming more and more advanced when it comes to safety, both in terms of vehicle structure and vehicle control functions. Most modern vehicles are equipped with advanced driver assistance systems that aim to assist the driver in a driving process. An example of an advanced driver assistance system is cruise control set to maintain vehicle speed.

More advanced adaptive cruise control systems are capable of dynamically adapting the vehicle speed, for example reducing speed for command vehicles. Additionally, some advanced driver assistance systems can be configured to avoid collisions, such as automatically braking the vehicle in some circumstances, or steering assist to steer away from the object in the vehicle's path if a collision is predicted. US20160280265 discloses a method for emergency steering support.

Although many of the advanced driver assistance systems provide useful assistance to the driver in the event of an imminent collision, there is still room for improvement with respect to accident avoidance in vehicle collision situations.

Brief Description of the Invention

In view of the prior art mentioned above, it is the object of the present invention to provide an improved collision avoidance method for a host vehicle. An enhanced evasive steering system configured to provide intervention action for a host vehicle is also provided.

According to a first aspect of the invention as defined in claim 1, there is provided a collision avoidance method for a host vehicle, the method comprising: detecting a target in the vicinity of the vehicle; determining that the host vehicle is traveling on a collision course with the target; detecting a steering action initiated by the user to direct the vehicle to one side of the target; determining a degree of understeer of the host vehicle; when the degree of understeer exceeds a first understeer threshold, controlling a steering control system of the vehicle to counteract the user-initiated steering action by applying a steering torque superposition to thereby reduce the degree of understeer.

The present invention is based on the understanding that drivers often overreact when attempting to move away to avoid a collision with a target. This often leads to vehicle understeer, particularly on low-friction roads. The present invention is therefore based on the understanding of counteracting the steering input initiated by the user to thereby prevent understeer, so that the vehicle can be safely driven beyond the target. In other words, the steering action initiated by the user is effectively reduced or damped by the counteracting steering provided by the steering system.

Accordingly, with the inventive concept, for an overreactive driver who turns too much in an evasive maneuver, instead of adding steering torque, the user's initial steering action is counteracted.

Furthermore, according to the first aspect of the invention, determining the duration of understeer, wherein counteracting user-initiated steering action is only performed when the duration of understeer time has exceeded a first threshold duration. For safety reasons, it is advisable to avoid accidental activation of the counter-steering. Therefore, it is advantageous to require that understeer has occurred for at least a threshold time period before countersteering is performed.

Counteracting user-initiated steering action is only performed as long as the understeer duration is within a second threshold duration that exceeds the first threshold duration. For reasons of functional safety, it is advantageous not to allow the countersteering to be active for too long. Therefore, a timeout limit is set by the second threshold duration.

According to one embodiment, determining a stability parameter value indicative of the driving stability of the host vehicle, wherein counteracting user-initiated steering action is only performed when the stability parameter value indicates that the host vehicle is stable. The stability parameter may indicate tire slippage below a threshold value, preferably in the linear regime, that is, that the vehicle is not “sliding”. The slip angle is the angle between the direction of travel of the tire contact patch and the direction of the wheel hub (i.e., the pointing direction of the wheel). The slip angle can be measured for one of the wheels on the rear axle of the vehicle. Another possible indicator of stability is the yaw rate, that is, the speed of rotation about the vertical axis. A yaw rate exceeding a threshold may indicate an unstable vehicle condition.

According to one embodiment, the degree of understeer may be a deviation between a calculated reference steering angle that is determined from a model and a measured actual steering angle of the host vehicle.

According to one embodiment, determining the vehicle-specific parameters and the vehicle driving parameters, and calculating the reference steering angle based on the vehicle-specific parameters, the vehicle driving parameters and the vehicle model.

The reference steering angle is the desired steering angle. The reference steering angle can be calculated using a mathematical algorithm that includes a vehicle model. Typically, vehicle driving parameters such as vehicle speed and yaw rate/lateral acceleration are measured and used as input to the algorithm. Vehicle-specific parameters, such as vehicle mass and tire cornering stiffness, can be estimated or retrieved elsewhere, for example from a vehicle parameter and online state-to-state estimation system. board.

The algorithm calculates the steering angle based on the vehicle model and parameters.

The measured steering angle is the actual steering angle. This angle is typically measured at the steering column with a steering angle sensor or the pinion angle through the vehicle's electrically assisted steering system.

The vehicle model may be the bicycle model that is assumed to be known per se.

According to one embodiment, a steering torque for counter-steering action may be determined based on the deviation between the calculated reference steering angle and the measured actual steering angle. Consequently, the steering torque for countersteering action can be determined based on the steering angles that are readily available directly related to the degree of understeer. The deviation between the calculated reference steering angle and the actual measured steering angle is a measure of the actual degree of understeer.

According to one embodiment, the steering torque for the countersteering action may be proportional to the deviation between the calculated reference steering angle and the measured actual steering angle.

According to one embodiment, the degree of understeer may be based on the understeer gradient. Therefore, an understeer situation can be captured earlier compared to using absolute understeer to judge the degree of understeer.

According to one embodiment, when the degree of understeer is subsequently determined to be below a second understeer threshold, which is less than the first understeer threshold, the steering control system is controlled to stop providing the steering action. counteracting direction. Countersteering torque can be disabled when the degree of understeer is determined to be below a threshold and the driver can control the vehicle himself.

According to a second aspect of the invention as defined in claim 9, there is provided an evasive steering system configured to provide an intervention action for a host vehicle to avoid a collision with a target, the evasive steering system comprising : a driving environment detection unit configured to detect a target in the vicinity of the host vehicle; a collision determination unit configured to determine that the host vehicle is on a collision course with the target; a steering control system configured to control the steering torque of the host vehicle; and a vehicle control unit configured to: detect a steering action initiated by the user to direct the vehicle toward a side of the target; determining a degree of understeer of the host vehicle and a duration of understeer; When the degree of understeer exceeds a threshold, control the vehicle steering control system to counteract the user-initiated steering action to reduce the degree of understeer only when the duration of understeer has exceeded the first threshold duration, and only as long as the understeer duration is within the second threshold duration that exceeds the first threshold duration.

According to one embodiment, the system may comprise a vehicle stability measurement unit configured to determine a stability parameter value indicative of the driving stability of the host vehicle, wherein the vehicle control unit is configured to control the steering control system to counteract user-initiated steering action only when the stability parameter value indicates that the host vehicle is stable.

According to one embodiment, the system may include a steering angle sensor for measuring an actual steering angle of the host vehicle, wherein the vehicle control unit is configured to: calculate the degree of understeer based on a deviation between a calculated reference steering angle that is determined from a model and the actual measured steering angle.

According to one embodiment, the vehicle control unit is configured to: determine a steering torque for countersteering action based on the deviation between the calculated reference steering angle and the measured actual steering angle.

The effects and characteristics of the second aspect of the invention are largely analogous to those described above in relation to the first aspect of the invention.

Furthermore, a vehicle comprising the evasive steering system is provided according to any embodiment of the second aspect.

A control unit may include at least one microprocessor, a microcontroller, a programmable digital signal processor or other programmable device.

Other characteristics and advantages of the present invention will become evident when studying the attached claims and the following description. One skilled in the art realizes that the different features of the present invention can be combined to create embodiments other than those described below, without departing from the scope of the present invention.

Brief Description of the Drawings

These and other aspects of the present invention will now be described in greater detail, with reference to the accompanying drawings showing embodiments of the invention.

Fig. 1 illustrates a host vehicle approaching a target vehicle;

The Figs. 2a-c are graphs illustrating the longitudinal distance required to reach a complete rest versus speed for different friction conditions;

Fig. 3 illustrates tire lateral force versus tire slip angle;

Fig. 4 illustrates a schematic summary of the exemplary application of embodiments of the invention;

Fig. 5 shows a functional box plot for embodiments of the invention;

Fig. 6 shows a functional box plot for embodiments of the invention;

Fig. 7 is a box diagram of an evasive steering system according to embodiments of the invention; and Fig. 8 is a flow chart of the steps of the method according to embodiments of the invention.

Detailed Description of Example Embodiments

In the present detailed description, various embodiments of the system and method according to the present invention are described. However, this invention may be represented in many different ways and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to the skilled person. Like reference numbers refer to like elements throughout.

Fig. 1 illustrates a schematic description of an example of a host vehicle 102 approaching a target 104 from behind traveling on a road 103. The road is delimited by outer edges 105 and 107, which may be lane markers. Here it is shown that the road has two lanes, lane 103a in which the target 104 and the host vehicle 102 travel, and an opposite lane 103b. The target here is a target vehicle 104.

The host vehicle 102 approaches the vehicle at a relatively high speed and risks colliding with the target vehicle 104. The driver of the host vehicle 102 may attempt to brake only and thus continue on its original course 109. However, depending on the conditions driving conditions, such as whether and the condition of the road surface, this approach may not be efficient in avoiding a collision.

Another approach is to attempt to follow the course 111 and thus turn towards the side of the target vehicle 104, with or without braking. The above two approaches will be briefly discussed.

The Figs. 2a-c are graphs showing the longitudinal distance required to reach a complete break versus speed for different friction between the road surface and the vehicle's tires. Fig. 2a represents a relative friction of 1, Fig. 2b represents the relative friction of 0.6, and Fig. 2c represents the relative friction of 0.2.

On each graph there are two curves, one representing braking alone (solid), and the other representing braking combined with steering (dashed).

In fig. 2a the curves are crossed at approximately 42 km/h, so for speeds above 42 km/h, the longitudinal distance necessary to come to a complete rest by braking alone (solid) exceeds that of combined braking and steering (discontinuous). For lower friction, for example, 0.6 as depicted in fig. 2b, the crossing is for an even lower speed at 33 km/h. Furthermore, for even lower friction, such as 0.2 represented by fig. 2c, the crossing is for an even lower speed at 18 km/h.

Consequently, from figs. 2a-c it can be concluded that for slippery roads, the inclusion of a steering action in the evasive maneuver is more efficient than a single braking action in avoiding collisions with a target ahead of the host vehicle.

However, the efficiency of steering towards the target side, as suggested by course 111 in fig. 1, it depends on the lateral tire force on the host vehicle tires.

Fig. 3 illustrates the lateral tire force (Fy) versus the tire slip angle (a) for the rolling wheel on dashed curve 302 and for a wheel locked on curve 304. The slip angle (a ) is the angle between the direction of travel and the pointing direction of the wheel hub, as illustrated in the tire diagram 300 shown in FIG. 3.

For a locked wheel, the lateral force can be given by the expression |jsFzsin(a), where |js is the coefficient of friction and Fz is the normal force between the tire and the road surface.

The rolling wheel curve 302 (dashed) shows that the lateral force Fy saturates relatively quickly at peak 306. For larger slip angles, the lateral force Fy decreases, indicating that the grip between the tire and the road surface the road is decreasing. For large slip angles, the lateral force of a rolling tire approaches that of a locked wheel.

Therefore, since the lateral force of the tire saturates quickly, more steering provides excessive tire lateral slip angle and understeer. This will result in less lateral acceleration and, therefore, in less lateral displacement of the vehicle and, consequently, in a greater risk of collision with the target in front. The invention alleviates the aforementioned problematic driving situation.

Fig. 4 illustrates a schematic summary of the exemplary application of embodiments of the invention. An evasive steering system is comprised of a host vehicle 100 shown here traveling on a road 103. The road is bounded by outer edges 105 and 107. The road is shown here to have two lanes, lane 103a being the ego lane. of the host vehicle 102 and an opposite lane 103b.

The vehicle 102 consists of a driving environment detection unit 202 configured to detect a target 104 in the vicinity of the host vehicle 102. The host vehicle 102 further comprises a collision determination unit 204 configured to determine that the host vehicle is in collision course with the target 104 and a steering control system 206 configured to control the steering torque of the host vehicle.

The host vehicle 102 further comprises a vehicle control unit 208. The vehicle control unit 208 receives information that the host vehicle 102 is on a collision course with the target vehicle 104 from the collision determination unit 204. The unit The control system then detects a user-initiated steering action to steer the host vehicle 102 toward the side of the target vehicle 104 to avoid a collision. The user-initiated steering action initiates the divert phase indicated in fig. 4.

The control unit 208 then determines the current degree of understeer of the host vehicle 102 as a result of the steering input by the driver. Determining the actual degree of understeer can be made by calculating a deviation between a calculated reference steering angle that is determined from a model and the actual measured steering angle.

The reference steering angle is the desired steering angle. The reference steering angle can be calculated using a mathematical algorithm that includes a vehicle model. Typically, vehicle driving parameters such as vehicle speed and yaw rate/lateral acceleration are measured and used as input to the algorithm. Vehicle-specific parameters, such as vehicle mass and tire cornering stiffness, can be estimated or retrieved elsewhere. The algorithm calculates the steering angle based on the vehicle model and parameters.

The measured steering angle is the actual steering angle. This angle is typically measured at the steering column with a steering angle sensor and/or the pinion angle through the vehicle's electrically assisted steering system. The vehicle may include a steering angle sensor (not shown) to measure an actual steering angle of the host vehicle.

10

When the vehicle control unit 208 determines that the degree of understeer exceeds a threshold, the vehicle control unit 208 controls the steering control system to counteract the steering input initiated by the user, as indicated by the steering wheel 402 and the direction of rotation of the flywheel 402 shown conceptually clockwise.

Consequently, as the host vehicle 102 approaches the target 104 and the driver attempts to turn to one side, that is, as indicated by the turning phase, the steering may be too excessive, which may result in a loss of lateral force. of the wheels and understeering. This leads to a heading of 404 and an imminent collision with target 104.

However, with the evasive steering system, oversteering is counteracted by an overlay of steering torque, as indicated by the steering wheel 402 and the direction of rotation of the steering wheel 402 shown conceptually. This leads to a recovery of the lateral force of the wheels and a reduction in understeer and, consequently, to better control of the trajectory and stability of the vehicle. Accordingly, the host vehicle 102 may be diverted rearward to travel along the safe route 406. During the reverse steering phase, the vehicle stability control systems may provide additional control of the steering of the vehicle. to avoid unstable driving, such as oversteering, etc.

Fig. 5 shows a functional box plot for embodiments of the invention. Box 502 represents a collision threat assessment, that is, to determine whether a collision is imminent. Additionally, box 504 represents understeer detection which may be based on various parameters such as lateral acceleration, steering wheel angle, vehicle yaw rate, etc. It is determined whether the understeer is above the first degree of understeer threshold. Additionally, a timer 506 may determine the time lapse of understeer and check the time lapse against a threshold duration as indicated on the box 508.

In some embodiments, a vehicle stability measurement unit functionally represented by 510 may determine that the vehicle is stable.

As indicated by the AND-gate concept 512, the evasive steering function, that is, to counteract the steering action initiated by the driver, is only activated when a threat is detected, and the understeer exceeds the threshold, and the Understeer time exceeds a threshold duration, and the vehicle is stable.

Fig. 6 shows a functional box plot for embodiments of the invention. In fig. 6, the deactivation of the evasive steering system is functionally exemplified.

As indicated in the conceptual OR-gate 514, the evasive steering function, i.e. to counteract steering action initiated by the driver, is deactivated when no threat is detected, or the understeer is below a second threshold of understeer, or the time span of understeer exceeds a second threshold duration, or the vehicle is unstable. The second threshold duration is a timeout limit to ensure that countersteering is not active for too long. Furthermore, the second understeer threshold is lower than the first understeer threshold to ensure that the driver can safely control the vehicle by himself.

Fig. 7 is a box diagram of an evasive steering system 200 according to embodiments of the invention. The evasive steering system 200 consists of a driving environment detection unit 202 configured to detect a target in the vicinity of the host vehicle.

Additionally, the system 200 comprises a collision determination unit 204 configured to determine that the host vehicle is on a collision course with the target. The collision determination unit 204 may comprise a processor or control unit, for example, part of the vehicle control unit 208 or part of another vehicle safety system used to predict the collision. The collision determination unit 204 may provide a signal to the vehicle control unit 208 that the host vehicle is on a collision course with a target.

A steering control system 206 composed of system 200 is configured to control the curvature of the host vehicle by applying a steering torque superposition. Steering torque is used to turn the vehicle's steerable wheels to a desired wheel angle that corresponds to the desired camber. The steering control system 206 is controlled by the vehicle control unit 208.

In some embodiments, the evasive steering system 200 comprises a vehicle stability measurement unit 210 configured to determine a stability parameter value indicating the driving stability of the vehicle. The vehicle control unit 208 is configured to provide the intervention action only when the host vehicle is determined to be stable.

The steering control system 206 may comprise an electrically assisted steering system. Therefore, the vehicle control unit 208 may request that a steering torque be added to the steering system through the electrically assisted steering system. The requested address pair overlap (T address) can be provided by:

Tdirection— Kp(Aref ~A re a l)

Where K® is a feedback gain factor and is an adjustable constant, A r e fes a reference steering angle that is calculated with respect to the steering profile required to counteract the steering action initiated by the driver, and A re a les the actual steering angle present.

Accordingly, the steering control system 206 integrated into the system 200 is configured to apply a steering torque superposition. Superposition steering torque is used to turn the vehicle's steerable wheels to a desired wheel angle to counteract user-initiated steering input.

The steering control system 206 may be composed of a controller that calculates the reference steering angle using, for example, a vehicle model. Additionally, the steering control system 206 may comprise an electrical machine for providing steering torque.

Additionally, the evasive steering system 200 may optionally include vehicle-to-vehicle communication units and/or vehicle-to-infrastructure communication units, and/or vehicle-to-device communication units, i.e., communication units 201 generally known as V2X communication with the “cloud” through a server to obtain information on the presence of other vehicles or objects in order to improve the detection capacity of nearby vehicles.

Fig. 8 is a flow chart of the steps of the method according to embodiments of the invention. In step S102, there is a target near the detected vehicle.

Subsequently, in step S104, it is determined that the host vehicle is moving on a collision course with the target. In step S106, a steering action initiated by the user to direct the vehicle to one side of the target is detected. As the driver steers the vehicle, a degree of understeer of the host vehicle is determined in step S108. When the degree of understeer exceeds a first understeer threshold, controlling a steering control system of the vehicle to counteract the steering action initiated by the user to thereby reduce the degree of understeer in step S110.

A vehicle according to the invention may be any vehicle operating on a road, such as a car, van, truck, bus, etc.

The vehicle control unit may include a microprocessor, microcontroller, programmable digital signal processor or other programmable device. The control functionality of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a cable system. Embodiments within the scope of the present disclosure include program products comprising a machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media may be any available media that can be accessed by a general-purpose or special-purpose computer or other processor-based machine. By way of example, such machine readable media may comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to transport or store the desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general-purpose or special-purpose computer or other processor machine. When information is transferred or provided over a network or other communications connection (whether wired, wireless, or a combination of wired or wireless) to a machine, the machine correctly considers the connection to be a machine-readable medium. Furthermore, any such connection is correctly called a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media.

Machine-executable instructions include, for example, instructions and data that cause a general-purpose computer, a special-purpose computer, or special-purpose processing machines to perform a certain function or group of functions.

Although the figures may show a sequence, the order of the steps may differ from what is described. Two or more steps can also be performed simultaneously or with partial concurrency. Such variation will depend on the software and hardware systems chosen and the designer's choice. All of these variations are within the scope of the disclosure. Likewise, software implementations could be accomplished using standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps.

The person skilled in the art realizes that the present invention is in no way limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

In the claims, the word “understand” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several elements mentioned in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be exploited. Any reference sign in the claims should not be construed as a limitation of the scope.

Claims (13)

1. A collision avoidance method for a host vehicle (102), the method comprising: - detect (S102) a target (104) in the vicinity of the vehicle; - determining (S104) that the host vehicle is traveling on a collision course (106) with the target; - detecting (S106) a steering action initiated by the user to direct the vehicle to one side of the target; - determine (S108) a degree of understeer of the host vehicle and A duration of understeer; the method characterized because it also includes: - when the degree of understeer exceeds a first understeer threshold, controlling (S110) a steering control system (206) of the host vehicle to counteract the steering action initiated by the user by applying a steering torque superposition to thereby reduce the degree of understeer only when the duration of the understeer time has exceeded a first threshold duration and only to the extent that the duration of the understeer is within a second threshold duration that exceeds the first threshold duration. 2. The method according to claim 1, comprising: - determining a stability parameter value indicative of the driving stability of the host vehicle, where counteracting user-initiated steering action is only performed when the stability parameter value indicates that the host vehicle is stable. 3. The method according to any of the preceding claims, wherein the degree of understeer is a deviation between a calculated reference steering angle determined from a vehicle model and a measured actual steering angle of the host vehicle. 4. The method according to claim 3, comprising: - determine the specific parameters of the vehicle and the driving parameters of the vehicle, and - calculate the reference steering angle based on the specific vehicle parameters, the vehicle driving parameters and the vehicle model. 5. The method according to any of claims 3 or 4, wherein a steering torque for counter-steering action is determined based on the deviation between the calculated reference steering angle and the measured actual steering angle. 6. The method according to claim 5, wherein the steering torque for the counter-steering action is proportional to the deviation between the calculated reference steering angle and the measured actual steering angle. 7. The method according to any of the preceding claims, wherein the degree of understeer is based on the understeer gradient. 8. The method according to any of the preceding claims, wherein when the degree of understeer is subsequently determined below a second understeer threshold that is less than the first understeer threshold, controlling the steering control system to stop provide counteracting steering action. 9. An evasive steering system (200) configured to provide an intervention action for a host vehicle (102) to avoid a collision with a target (104), the evasive steering system comprising: - a driving environment detection unit (202) configured to detect a target in the vicinity of the host vehicle; - a collision determination unit (204) configured to determine that the host vehicle is on a collision course with the target; - a steering control system (206) configured to control the steering torque of the host vehicle; and - a vehicle control unit (208) configured to: - detect a steering action initiated by the user to direct the vehicle to one side of the target; - determine a degree of understeer of the host vehicle and the duration of the understeer; characterized in that the system also includes: - when the degree of understeer exceeds a threshold, control the steering control system of the vehicle to counteract the steering action initiated by the user and thus reduce the degree of understeer only when the duration of understeer has exceeded a first threshold duration and only as long as the understeer duration is within the second threshold duration that exceeds the first threshold duration. 10. The evasive steering system according to claim 9, comprising: - a vehicle stability measurement unit (210) configured to determine a stability parameter value indicative of the driving stability of the host vehicle, where the vehicle control unit is configured to control the steering control system to counteract user-initiated steering action only when the stability parameter value indicates that the vehicle is stable. 11. The evasive steering system according to any of claims 9 and 10, comprising a steering angle sensor for measuring an actual steering angle of the host vehicle, wherein the vehicle control unit (208) is configured to: - calculate the degree of understeer based on a deviation between a calculated reference steering angle determined from a model, and the actual measured steering angle. 12. The evasive steering system according to any of claims 9 to 11, wherein the vehicle control unit is configured to: - determine a steering torque for countersteering action based on the deviation between the calculated reference steering angle and the measured actual steering angle. 13. A vehicle comprising the evasive steering system according to any of claims 9 to 12.